This invention relates to camshafts having cams supported for limited rotation thereon and to methods for producing such camshafts.
In German Offenlegungsschrift No. 32 34 640, a camshaft having cams mounted for limited rotation thereon utilizes in an advantageous manner forces which inevitably occur during valve operation, such as inertial forces and the closing force of the valve-closing spring and which are dependent on the revolutions per minute, to produce a change in the valve operation time which is dependent on the rpm. This is often desirable for the control of gas intake and exhaust valves, particularly for automotive internal combustion engines.
The arrangement described in that publication is designed so that the cam has a sleeve-shaped area supported directly on the camshaft and one component of a limited angular motion coupling between the camshaft and the cam, preferably a dog-like projection, is mounted on the camshaft. In the described arrangement, the dog-like projection is provided by a strip mounted in a recess in the camshaft.
To modify the gradient of the valve lift curve produced by this camshaft arrangement, a damper is provided. The damper consists of a throttle bore in the dog-like projection and a hydraulic fluid in a cam recess which receives the projection and permits limited angular motion of the projection therein. The damping fluid can be supplied to the recess through a flap valve from a longitudinal bore in the camshaft.